JPH0229232Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a swirl chamber type diesel engine.

Diesel engines often use a swirl chamber type in which a swirl chamber is provided in the cylinder head, and the highly compressed air introduced from the main combustion chamber and fuel are mixed and ignited in the swirl chamber. There is. This swirl chamber type diesel engine generally has a cylinder hole formed in the cylinder block, and a recessed hole in the cylinder head that opens at the lower surface of the cylinder head and is partially located outside the cylinder hole, and has a nozzle orifice. A swirl chamber is formed by fitting and fixing an insert having a diameter into the opening of the recessed hole. The cylinder head and the cylinder block are coupled with a gasket interposed between opposing surfaces of the two at the cylinder periphery.

In such a structure, although the insert is fitted into the recessed hole while being positioned in the vertical direction by corresponding steps provided on both sides, there are manufacturing and installation errors, so
It is unavoidable that some level difference will occur between the surface of the insert and the lower surface of the cylinder head. in this case,
If the surface of the insert protrudes below the lower surface of the cylinder head, this protruding portion will interfere with the sealing by the gasket, so the insert is designed in advance so that a step is created so that the surface of the insert is recessed slightly above the lower surface of the cylinder head. It is necessary to do so. However, if this is done, a gap will be created between the insert and the gasket outside the cylinder hole when the engine is assembled.
For this reason, especially when trying to downsize the engine by narrowing the distance between the outer periphery of the cylinder hole and the outer surface of the cylinder block, the sealing performance around the cylinder hole tends to deteriorate, and the above-mentioned gap communicates with the combustion chamber. There were problems such as a decrease in air utilization efficiency due to the large amount of space.

A known technique that focuses on this problem is disclosed in Japanese Patent Application Laid-Open No. 151239/1983, which discloses that the upper and lower portions of the gasket core (metal core) located below the insert Metal inlays are attached to both sides, and protrusions are provided on the inner and outer peripheries of the inlays, so that when the engine is assembled, these protrusions come into contact with the surface of the insert and the top surface of the cylinder block, thereby sealing these parts. However, with this structure, the inlay is hard and its protrusions have poor elasticity, which requires a high degree of machining accuracy and makes manufacturing cumbersome.Moreover, manufacturing errors can cause damage to the insert surface and the bottom surface of the cylinder head. It is difficult to sufficiently absorb variations in the level difference between the insert surface and the lower surface of the cylinder head, and it is particularly difficult to properly seal the boundary step between the insert surface and the lower surface of the cylinder head.

In view of these circumstances, the present invention improves the sealing performance between the surface of the insert that forms the nozzle of the swirl chamber and the top surface of the cylinder block, reliably prevents the creation of a space in this area, and furthermore. The present invention provides a swirl chamber type diesel engine that has a simple structure and is easy to manufacture.

That is, the present invention provides a swirl chamber type diesel engine in which the insert is fitted into the recessed hole of the cylinder head in such a manner that the insert surface is recessed with a slight step above the lower surface of the cylinder head, and the insert is inserted into the recessed hole of the cylinder head with a slight step above the lower surface of the cylinder head. A soft member made of a heat-resistant synthetic resin containing a soft metal, which is softer than the grommet part of the gasket and the cylinder head and has higher heat resistance, is placed in at least the part of the concave portion below the insert surface that corresponds to the gasket. This is what I did.

Embodiments of the present invention will be described below with reference to the drawings.

In FIGS. 1 and 2, 1 is a cylinder block, 2 is a cylinder head, and 3 is a gasket interposed between opposing surfaces of cylinder block 1 and cylinder head 2. A cylinder hole 4 is formed in the cylinder block 1, a piston 5 is fitted into the cylinder hole 4, and a main combustion chamber 6 is formed between the piston 5 and the lower surface of the cylinder head 2. On the other hand, the cylinder head 2 has a swirl chamber 7.
is formed. The swirl chamber 7 is formed by fitting and fixing an insert 9 into the lower end opening of a recessed hole 8 provided in the cylinder head 2. The insert 9 includes the main combustion chamber 6 and the swirl chamber 7. A spout 1 inclined in a predetermined direction to communicate with
0 is set. Further, inside the swirl chamber 7, a fuel injection nozzle 11 and a glow plug 12 for preheating when starting the engine are exposed. Then, in the compression process, a part of the intake air in the main combustion chamber 6 is introduced into the vortex chamber 7 through the jet nozzle 10 to generate a vortex, and after fuel is injected into this vortex and ignited, the fuel is ignited. is ejected from the nozzle 10 into the main combustion chamber 6 for diffusion combustion.

The recessed hole 8 is provided near the periphery of the cylinder hole 4 and opens on the lower surface 13 of the cylinder head 2.
In addition, a portion thereof is located outside the cylinder hole 4. For this recessed hole 8, the insert 9 is inserted into the recessed hole 8.
Step portion 14 on the inner peripheral surface and corresponding insert 9
By abutting the stepped portion 15 on the outer circumferential surface, it can be mounted in a vertically positioned position.
In this case, by designing in advance the distance l ₁ from the step 15 to the surface 16 of the insert 9 to be somewhat smaller than the distance l ₂ from the step 14 to the lower surface 13 of the cylinder head 2, the length of the insert 9 can be reduced. Surface 1
A step l3 is provided between both surfaces 13 and 16 so that the cylinder head 6 is recessed above the lower surface ₁₃ of the cylinder head 2.

The gasket 3 is formed to correspond to the upper surface of the cylinder block 1 outside the cylinder hole 4, and has a main portion 3a made of asbestos or the like.
It consists of a grommet 3b made of steel plate or the like which is placed over a predetermined range of the upper and lower surfaces from the inner circumferential end. The inner circumferential end surface of this grommet 3b surrounds the space above the cylinder hole 4, and the insert 9
The portion located outside the cylinder hole 4 faces the upper surface of the grommet 3b. Note that an inner ring 3c is provided near the inner circumference inside the grommet 3b as required.

A grommet portion of the gasket 3 and a grommet portion of the gasket ₃ are located in the recessed portion below the insert 9, which is created by the step l3 between the surface 16 of the insert 9 and the lower surface 16 of the cylinder head 2, in an area located outside the cylinder hole 4. A soft member 17 that is softer than the cylinder head 2 and has higher heat resistance is arranged. The soft member 17 is made of a heat-resistant synthetic resin such as an aromatic cyclic polyester resin containing a soft metal such as aluminum or copper. And the second
As shown in the figure, the step is formed in advance to be slightly thicker than the step _l3 .

In this swirl chamber type diesel engine, when the cylinder block 1 and the cylinder head 2 are connected with bolts or the like with the gasket 3 interposed therebetween during engine assembly, the surface 16 of the insert 9 and the gasket are connected. The gap between the grommet portion 3 and the upper surface of the grommet portion is completely filled with the soft member 17. Therefore, the sealing performance of this part is improved, and since no extra space is created in this part, the air utilization efficiency is also improved. Also,
The soft member 17 is softer than the grommet portion of the gasket 3 and the cylinder head 2, and as the soft member 17 comes into pressure contact with the gasket 3, the soft member ₁₇ is compressed. It has excellent absorbency against variations in the temperature, is easy to manufacture and assemble, and can maintain good sealing performance over a long period of time. In other words, if a member that fills such a gap is harder than the grommet portion of the gasket 3 and the cylinder head 2, this member will cause the gasket 3 to
The grommet portion of the grommet is compressively deformed, and as the engine is operated repeatedly in this state, the restorability of the grommet portion may deteriorate due to thermal effects, leading to a decrease in sealing performance.However, in the present invention, the soft Since the compressive force is absorbed by the member 17 and the compressive deformation of the grommet portion of the gasket 3 is suppressed, the above-mentioned disadvantages are also prevented.

In particular, since the soft member 17 is made of a heat-resistant synthetic resin containing a soft metal, superior functionality can be obtained compared to, for example, a case where it is formed only from a soft metal or a case where it is formed only from a heat-resistant synthetic resin. In other words, if such a member is formed only from a soft metal such as aluminum or copper, it is difficult to make the metal alone flexible enough to easily deform the relatively large area at the bottom of the insert. Therefore, it is difficult to eliminate the compressive deformation of the grommet portion, and if the grommet portion is made of only heat-resistant synthetic resin, the adhesiveness with the insert is poor and peeling is likely to occur. On the other hand, if the soft member 17 is made of a heat-resistant synthetic resin containing a soft metal, it will have sufficient flexibility to absorb the compressive force and prevent compressive deformation of the grommet portion, and will have sufficient flexibility for the insert 9. It is possible to achieve both sufficient adhesion and peeling resistance.

In the above embodiment, the soft member 17 is arranged only in the portion below the surface of the insert 9 that corresponds to the gasket 3, but as shown in FIG. Alternatively, a soft member 17' may be arranged, and a through hole 18 corresponding to the nozzle 10 may be formed in the soft member 17'.

As described above, the swirl chamber type diesel engine of the present invention has a material made of a heat-resistant synthetic resin containing a soft metal in the recess below the insert surface, which is created by the step between the insert surface and the lower surface of the cylinder head. A soft member that is softer than the grommet portion of the gasket and the cylinder head and has higher heat resistance is arranged so that the gap between the surface of the insert and the gasket is filled with the soft member. Therefore, the sealing performance of this part is improved, and the air utilization efficiency is also improved. Furthermore, manufacturing and assembly are simple, and the effect of suppressing compressive deformation of the grommet part of the gasket and the adhesion of the above-mentioned soft member to the insert are improved. It is rich in water and can maintain effects such as improved sealing performance over a long period of time.

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing one embodiment of the present invention;
The figure is an enlarged sectional view of the main parts in an exploded state, and FIG. 3 is an exploded sectional view showing another embodiment. 1... Cylinder block, 2... Cylinder head, 3... Gasket, 4... Cylinder hole, 7...
... Vortex chamber, 8 ... Recessed hole, 9 ... Insert, 1
7, 17'... Soft member.

Claims (1)

[Scope of utility model registration request] A cylinder block having a cylinder hole and a cylinder head having a swirl chamber are connected with a gasket interposed between opposing surfaces of the two, and the swirl chamber is opened at the lower surface of the cylinder head and a portion of the cylinder head is connected to the cylinder head. At the opening of the concave hole located outside the hole,
In a swirl chamber type diesel engine formed by fitting an insert having a jet nozzle, the insert is fitted into the recess so that the surface of the insert is recessed with a slight step above the lower surface of the cylinder head. At the same time, at least the part of the recess under the insert surface caused by the above-mentioned step that corresponds to the gasket is made of a heat-resistant synthetic resin containing a soft metal, which is softer and more heat-resistant than the grommet part of the gasket and the cylinder head. A swirl chamber type diesel engine characterized by the arrangement of highly flexible soft members.